Driving mechanism for bicycles.



No. 639,295. Patented Dec. l9, I899. 5

n. F. ROBISON. DRIVING MECHANISM FOR BICYCLES.

(Application filed Aug 19, 1897.) (No Model.)

PATENT nurse. I

ROBERT E. ROBISON, OF CHICAGO, ILLINOIS.

DRIVING lVi-ECHANI SM FOR BICYCLES.

SPECIFICATION forming part of Letters Patent No. 639,295, dated December19, 1899. Application filed August 19, 1897. Serial No. 648,772. (Nomodel.)

To MZZ whom it may concern:

Be it known that I, ROBERT F. ROBISON, a citizen of the United States,residing at Ohicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Driving Mechanism forBicyles; and I do hereby declare the following to be a f ull, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

This invention relates to improvements in driving mechanism for bicyclesand similar vehicles, and has for its object to provide an arrangementof this character that will dis pense with and take the place of theordinary sprocket-chain.

In the drawings, Figure 1 is a side elevation embodying the improvedfeatures, the relative position of the frame parts being indicated indotted lines; and Fig.2, abroken away part elevation and part section online 2, Fig. 1, looking in the direction indicated by the arrow.

A represents the center stay member of the frame of a bicycle; A, thelower main tube; A A the back forks; A the backstays; A the hanger; B,the crank-axle, and B B the crank-arms mounted on the respective endsthereof. 4

A gear-wheel C is rigidly mounted on the crank-axle adjacent to one endand on the inner side of the crank-arm, as shown in Fig. 2. The upperend of an angular bracketD is clamped to the center stay member of theframe and from that point extends outwardly and then downwardly, thelower terminal end extending inwardly at right angles and being clampedon one of the back-fork members A This bracket will consist, ordinarily,of two companion parts Ct a, bent into the required shape, the upperends of which encircle the center stay A and are locked in place bybolts a, while the lower ends, embracing a member of the back forks, arelocked together by the bolts (L The two parts comprising the bracket Dare spread apart at a point between the respective ends to form a seatfor the gear wheel E, mounted therein. The

toothed periphery of the gear-wheel E projects beyond the edges of thebracket parts and engages with the gear-wheel (l, mounted on thecrank-axle. The gear-wheel E is cut away, Fig. 2, on each side of theprojecting toothed periphery to form the annular shoulder-bearings a awhich are provided with grooves 61 The adjacent annular edges of thebracket parts are provided with grooves I), which are in line with thecorresponding grooves in the gear-wheel E. These grooves are filled withballs I) and provide a ballbearing for the wheel E. The bearing-ballsare inserted in place through a suitable opening provided in theinclosing bracket. The two bracket parts a a are provided with open ingsb at each side of the gear-wheel E. The companion bearing-pins (Z (Z areinserted in the respective sides of the wheel E and are setdiametrically opposite each other, so as to ease and facilitate therotary action, making the movement more positive and dispensing with thedead-points. The frontends of the companion connecting or driving rods FF are connected to the pins d d.

The upper end of a second angular bracket G is clamped to one of theback-stay tubes A and the lower end clamped to one of the backfork tubesA bringing the same in line with the bracket D. The outer side of thebracket G is broken away to show a second gear-Wheel H, which isprovided with a ball-bearing in bracket G. These parts are exactduplicates of the companion bracket D and gear-Wheel E, so that thedetail description ofone answers for both. The gear-wheel H is providedon each side with bearing-pins g g, set at opposite points, and have therear ends of the driving-rods F F connected thereto. The gear- Wheel Hengages with gear-Wheel K, mounted arrangement provides a simple,positive, and convenient driving connection between the crankaxle andthe rear-wheel axle of a bicycle and possesses advantages over that ofother devices for a similar purpose.

Having thus described my invention, What I claim as new, and desire tosecure by Letters Patent, is

1. In driving mechanism for bicycles the combination with, thecrank-axle, of a gear- Wheel mounted thereon, the two-part angularbracket, having its upper and lower ends secured to the center staymember of the frame and the back fork respectively, the

on the axle h of the rear driving-Wheel. This gear-wheel mounted in saidbracket, the two parts of which are spread apart at a point between therespective ends to form a seat for the gear-Wheel mounted thereon andengaging with the gear-Wheel on the crank-shaft, the rear wheel and itsaxle, and the companion connecting-rods, for transmitting the requiredmotion thereto, substantially as described.

2. In driving mechanism for bicycles, the combination with thecrank-axle, of a gearwheel, mounted thereon, a two-part angular bracket,having its upper and lower ends secured to the center stay member andback fork of the frame, the gear-wheel, seated in said bracket andengaging with the gearwheel on the crank-shaft and being cutaway on eachside of its toothed periphery to form shoulder-bearings in which areformed an n ular-grooves, the said bracket being provided interiorlywith corresponding grooves, and the bearing-balls, inserted therein,substan tially as described.

3. In driving mechanism for bicycles, the combination with thecrank-shaft, of a gearwheel mounted'thereon, a two-part angular bracket,provided interiorly with annular grooves, the center stay member of theframe and the back fork, to which the respective upper and lower ends ofsaid bracket parts are clamped, the gear-wheel, seated in said bracketand provided on each side of its toothed periphery with annular groovescorvrespondingxto the grooves in said bracket,

In testimony whereof I affix my signature in presence of two witnesses.

ROBERT F. ROBISON.=

Witnesses:

L. M. FREEMAN, L. B. COUPLAND.

